I'm thinking to get this tumbler:
https://www.frankonia.de/374034/259896/productdetail.html
https://www.youtube.com/watch?v=oowv-KTYf7Y
This TopShot CTI 3500 also goes by the name of SmartReloader 747. Most of these are sold through gun shops for cleaning bullet casings.
It's 42cm in diameter which is pretty large. Most others are about 30-35cm or even less. I'm trying to decide between this one, and the Lyman 2500, which is smaller. The issue is that if both have the same motor power, the larger one has less vibrating force compared to the smaller one as it has to move more material.
But the smaller ones may not be able to submerge my parts completely in the media. My parts are about 115mm x 80mm x40mm. Most of these machines have a center column dividing the tub, so you'll have to divide the diameter in half and subtract a bit to get the maximum sized parts you can fit in them.
As for the media, I've found some cheap ones, 25kg of ceramic triangles for 70 Euros, or 1kg for 5 Euros.
https://www.zujeddeloh.de/artikel582.html
The sizes are 4x4mm, and comes in 3 different abrasive strengths. I have no idea what strength to get, and I was hoping for something smaller and more round, like 2mm or 3mm. But other shops sell 1kg bags for 15 Euros.
The ones you've found in your part from Shapeways look something like this:
https://perfecta.bplaced.net/product_info.php?info=p202_keram ikschleifkoerper-kvsacc.html
Or maybe porcelain polishers
https://perfecta.bplaced.net/product_info.php?info=p2_poliers tifte-porzellan.html
Here is more information about shapes and sizes.
https://www.cimaceramiche.com/download.htm
https://www.walther-trowal.com/en/products/chips-compounds/ce ramic-media/
I was thinking this first pass with the ceramic triangles would be an aggressive grind to get rid of the stepping lines, and then maybe it would be good to make a second pass with these round porcelain balls. However, these things are really expensive at the only one shop I could find that sells it.
https://perfecta.bplaced.net/product_info.php?info=p190_polie rkugeln-porzellan-3-mm.html
Although, it would be much easier to use one type of media and dump the parts in one go. Changing media and cleaning up would be a hassle.
I can't speak German, so my searching abilities are limited. Unless anyone knows where else to get these things in Europe?